The present invention relates to gassification of carbon containing waste and refuse particularly refuse that includes organic compounds, and more particularly the invention relates to the gassification of refuse wherein a very hot liquid as well as an oxidation medium is brought into contact with the refuse.
It is generally known that, strictly from a stand point of volume and quantities involved, commercial and household refuse garbage etc., constitutes an ever increasing problem particularly if the common practices continues to first deposit the material in an particular location. In the past, therefore, techniques have been developed and used to some extent to burn the garbage or to pyrolyze it. Here, one has to consider the side effect that the thermal energy developed by either form of combustion could be used some form or another. For example, in case of burning of refuse, one can consider a heating value from about 2 to 2.5 kilowatt hours per kilogram. However, it is also well known that in the case of combustion and burning of refuse highly aggressive gases are produced, for example, hydrochloric acid; HF, SO2 and NOX. These gases as captured in the combustion products which constitute exhaust fumes and smoke and have to be removed therefrom, which is an expensive procedure and requires a considerable amount of energy. In many cases such a removal proved to be practically impossible, at least not to the desired degrees considering ecological requirements.
In some cases, refuse is processed by low temperature carbonization under utilization of heat supplied thereto, but under exclusion of air. The problem of contamination of the carbonization gases still remains. Moreover in these cases, certain desired gases such as CH4, H2 and CO are produced but in addition contaminants such as H2S, HCl, HF, tar, oil, phenoles and undesirable hydrocarbons are produced. These contaminating components therefor have to be removed which again is extensive and expensive, usually involving an extensive chemical procedure whereby particularly it is necessary to separate the desirable from the undesirable by-products of the carbonization process.
Aside from the problem of generally disposing refuse, certain special refuse to be disposed poses special problems. For example, certain organic compounds and materials are part of garbage and industrial waste, such as polychlorinated biphenyl (PCB's) hexlal-chlorocyclohexane, (HCH), and dioxine. All these poisionous substances can be neutralized or destroyed only with great difficulties.
A method is known for the gassification of household refuse and is disclosed in German printed Patent Application 3,212,534. Accordingly, the refuse is introduced into a hot iron baph having a temperature between 1130 and 1600 degrees centrigrade, and an oxidation medium is also added. In this method than the refuse is granulized i.e. chopped into particles of at least 50 millimeter size and added to the molten iron, underneath the surface of the bath. The chopping of refuse is again a energy extensive process and in case of certain poisonous refuse the procedure is quite dangerous. Also, introducing the refuse from underneath the surface of molten iron is a ratherh extensive and expensive procedure. Moreover, it is not certain that all of the refuse particles assume the temperature of the molten metal which however is essential in some cases.